1. Technical Field of the Invention
The present inventions relate to semiconductor chips and, more particularly, to chips in a system with skew control between clock and data.
2. Background Art
Modules include circuit boards, such as printed circuit boards (PCBs), that have chips (integrated circuits) on one or both sides of the modules. Examples of memory modules include single in line memory modules (SIMMs) and dual in line memory modules (DIMMs). The modules are positioned on motherboards, which may also support a controller, such as a memory controller (which may be integrated with other chipset functions or in a processor).
Typically, a motherboard includes at least two slots to receive modules. Some motherboards, particularly those for server systems, include slots for more than two modules. Systems typically work with different types of modules. Some modules have X number of chips. Other modules have 2X or 4X chips. Some modules have chips on both sides of the PCB. Other modules have chips only one side of the PCB. To be versatile, a memory controller is often capable of functioning under a variety of combinations of different module types in the slots or the absence of modules in a slot.
A path typically has at least one termination device (called a termination), such as a termination resistor, to allow electrical energy to dissipate. Terminations may be positioned on the die and be controllably switchable between enable and disabled states. In other words, the on die termination may be enabled to dissipate energy at some times and be disabled so as not to be able to dissipate energy at other times.
A write clock is a clock signal used in writing data. A write clock for a memory system may be a free running write clock, meaning it runs whether or not data is to be written. By contrast, a strobe may run only when there is a data to be transmitter.